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Transient pyelonephritic changes on 99mTechnetium-dimercaptosuccinic acid scan for at least five months after
1Department of Pediatrics and Nuclear Medicine, Karolinska Institute, Huddinge University Hospital, Sweden.
Insights
Technetium-dimercaptosuccinic acid (DMSA) scans reveal that renal changes after urinary tract infections (UTIs) can persist longer than expected. For accurate assessment of permanent damage, DMSA scans should be conducted over five months post-infection.
Area of Science:
- Pediatric Nephrology
- Diagnostic Imaging
- Infectious Diseases
Background:
- Urinary tract infections (UTIs) are common in children and can lead to renal scarring.
- The role of 99mTechnetium-dimercaptosuccinic acid (DMSA) scans in evaluating UTI-related renal damage requires clarification.
Purpose of the Study:
- To determine optimal timing for DMSA scans in investigating pediatric UTIs.
- To track the evolution of renal changes from acute pyelonephritis to permanent damage.
Main Methods:
- Prospective study of 185 children with symptomatic UTIs.
- Serial DMSA scans performed within 5 days, at median 9.2 weeks, and ~2 years post-infection.
- Micturition cystourethrography (MCU) performed at the 2-year follow-up.
Main Results:
- 85% of children had abnormal DMSA scans at infection onset, decreasing to 36% at 2 years.
- Abnormal DMSA scans within 20 weeks normalized in 38% by the third study.
- Persistent renal changes were more frequent in children older than 4 years.
- Vesicoureteral reflux (VUR) grade ≥3 was associated with abnormal DMSA scans at 2 months.
Conclusions:
- DMSA scan abnormalities after an initial UTI may resolve over a longer period than previously assumed.
- Performing DMSA scans more than 5 months after UTI is recommended to identify persistent renal damage.
- Early DMSA scan findings in children with significant VUR may not reflect long-term renal status.
Abstract:
A prospective study was performed on 185 children with symptomatic urinary tract infection (UTI), 130F and 55M, having a median age of 0.9 y (range 0.1-9.8) at the time of UTI. The aim of the study was to find out how the 99mTechnetium-dimercaptosuccinic acid (DMSA) scan should be used to investigate UTI, and to follow the development of renal changes during pyelonephritis into subsequent permanent renal damage. All children were investigated with a DMSA scan within 5 days after admission and after 3.9-53.3 (median 9.2) weeks, and 159 were studied again after approximately 2 y (range 1.5-3.9 y). They all underwent micturition cystourethrography at the time of the second study. At the time of infection, the DMSA scan was abnormal in 85% of the children, in 58% at the first follow-up and in 36% at the second follow-up. An abnormal DMSA scan performed within 20 weeks from infection became normal in 38% of cases on the third study, while only 1/10 abnormal DMSA scans performed more than 20 weeks after infection became normal after 1.5-3.9 y. Persistent renal changes were more common in children > 4 y of age than in children < or = 1 y of age. Two months after the presenting infection, it was unusual to see a normal DMSA scan in a child with a VUR gr. > or = 3. The study suggests that DMSA changes after an index UTI may be transient for a longer period of time than has been previously considered. Therefore, in order to detect persistent changes, a DMSA scan should be performed more than 5 months after UTI.